Leak-proof primary cell

ABSTRACT

A leak-proof electrochemical cell having a cylindrical can closed on its bottom end, and originally open at its top end, with an internal peripheral bead as a seat for a plastic disc to be seated on the bead to cover the elements within the cell, and to receive the crimped end of the can for closure with the plastic disc constructed to have a central co-axial bore and coaxial hub around the bore to hold an anode collector in the shape of a nail whose head supports one of the terminals of the cell, here specifically the negative cap or terminal, welded to said head, and the plastic disc performs the additional function of closing the usual separator, with no intervening structure between it and the separator, to assure greater confining control of the electrolyte in said separator. The plastic disc top also constructed unitarily of full can diameter, and has an annular border disposed to provide a tight seating fit in the can at the bead as a seat, and is held in place by the crimped edge rim of the can to assure a substantially hermetic seal between the disc border and the can. An external metal jacket surrounds and is insulated from the can and has both ends crimped, with the top crimp holding the negative cap terminal to impress an additional pressure force on the metal crimped onto the plastic disc, to assure a hermetic seal under continuous pressure between those engaging surfaces of said plastic disc border and of said crimped metal at the can top.

United States Patent Ralston et al.

[451 May 16, 1972 LEAK-PROOF PRIMARY CELL [72] Inventors: Robert E. Ralston, Spring Valley; Yung Ling Ko, Peekskill, both of NY.

[73] Assignee: P. R. Mallory & Co. Inc., Indianapolis,

Ind.

[22] Filed: Apr. 9, 1970 [21] Appl.N0.: 26,943

[52] US. Cl [51] Int. Cl. [58] Field of Search ....136/l07, 136/169 ..ll0lm 21/00 136/107, 83, 100, 131-135, 136/175, 169

Primary Examiner-Anthony Skapars Att0rneyR0lJert Levine s7 ABSTRACT A leak-proof electrochemical cell having a cylindrical can closed on its bottom end, and originally open at its top end, with an internal peripheral bead as a seat for a plastic disc to be seated on the bead to cover the elements within the cell, and to receive the crimped end of the can for closure with the plastic disc constructed to have a central co-axial bore and coaxial hub around the bore to hold an anode collector in the shape of a nail whose head supports one of the terminals of the cell, here specifically the negative cap or terminal, welded to said head, and the plastic disc perfonns the additional function of closing the usual separator, with no intervening structure between it and the separator, to assure greater confining control of the electrolyte in said separator. The plastic disc top also constructed unitarily of full can diameter, and has an annular border disposed to provide a tight seating fit in the can at the bead as a seat, and is held in place by the crimped edge rim of the can to assure a substantially hermetic seal between the disc border and the can. An external metal jacket surrounds and is insulated from the can and has both ends crimped, with the top crimp holding the negative cap terminal to impress an additional pressure force on the metal crimped onto the plastic disc, to assure a hermetic seal under continuous pressure between those engaging surfaces of said plastic disc border and of said crimped metal at the can top.

7 Claims, 4 Drawing Figures 2 Shoots-Sheet I Patented May 16, 1972 Patented May 16, 1972 2 Sheets Sheet 7. I

canuer 4/ down ward LEAK-PROOF PRIMARY CELL DESCRIPTION OF THE INVENTION This invention relates to electrochemical cells, and, more particularly, to an alkaline dry cell of improved design construction, to provide a greater assurance of stability in operating characteristics, and particularly to provide a construction for preventing leakage of the electrolyte to the outside of the cell.

In the evolution and development of alkaline dry cells, the greatly improved type of operation obtained from that type of cell has led to its use in many fields of application where primary electro-chemical cells have generally not been available for such use.

In many cases the optimum usage of such improved cells in those new applications nevertheless required some changes in the structural design, in view of changed dimensions relative to prior cells, so that as a result the problem of satisfactorily sealing a cell to prevent electrolyte creepage was always a recurring problem with each new design and dimensional change.

At the same time, of course, since such primary batteries have been essentially throwaway units which become used up during their normal operation and are then thrown away when the chemical components therein have essentially been completely converted to non-useable or non-active condition within the cell, the usual economic goal of low-cost production has always been one of the pressing and desirable factors in the evolutionary development of cells of this type.

In all cases, with any change in previous structural design or previous dimensions, in order to fit into a new environment and application, there intruded the ever-pressing problem of assuring that such new design and such new dimensions would not result in conditions that would promote or permit leakage or creepage of the electrolyte to undesired regions of the cell. Thus, the problem of leakage and creepage prevention has been always present, irrespective of any other improvements that may have been made during the progressive development of those cells.

The present invention is directed to certain novel features of redesign in a cell, in which particularly new structural design features leading to better sealing of the cell have been achieved, while providing for low-cost production.

As a result of such assured hermetic sealing of the cell, long shelf life is assured without any leakage of the electrolyte out through the cell ends that would lead to the formation of encrustations, that would not only disfigure the appearance of the cell but would raise doubts as to whether the cell was still in operative condition.

In accordance with this invention, in a general form of construction of a cell embodying the features provided by this invention, the usual cathodic and anodic chemical elements with a suitable separator are disposed in a cathodic metal can or cup, closed at the bottom, and initially fully open at the top, to permit unimpeded and direct insertion of those chemical elements and the separator into said can during manufacture. The can is then appropriately reformed and shaped to provide an internal peripheral bead disposed slightly below the top edge of the open end of the can, such bead being provided to serve as a seat for a plastic plate or disc to serve as a closure element, which is then inserted axially into the can to seat and rest on the bead and to receive the can crimp for closure. A radially recessed annular shoulder is provided in the side of the plastic disc to seat on the bead. The plastic disc serves also as a support for an anode collector in the shape of a nail having a flathead onto which a terminal plate has been previously welded. The plastic top is inserted into the cell by manipulation of the plastic top to its rest position onto the inner bead in the can. After that insertion of said disc into the can, the open end edge of the can is crimped over the top outer surface of the plastic disc above the shoulder which rests on the bead.

The separator between cathodic material and the electrolyte, defines a central chamber to accommodate the electrolyte. A feature of the construction and operation herein, is that the plastic disc closure limits outward movement of the electrolyte from its chamber, and prevents contact between the electrolyte and metal elements of the cell.

The plastic disc serves also to press on the top of the separator between the anode and the cathode, and said disc serves to close the top of the chamber for the electrolyte employed in this cell.

The plastic disc is thus a novel unitary insulating element in such cells to support an anode collector, to close the separator chamber for the electrolyte, to receive the closing and sealing crimp of the open can end in assembly, and to support an external terminal plate, at the end of the cell, that is welded to the nailhead of the anode collector.

One of the objects of this invention to provide a unitary plastic cell top or disc having a resilient vertical edge portion in a position to receive the crimp from the container can for better seal characteristics at such crimp.

Another object of this invention is to provide said unitary plastic .cell top or disc with a central bore to receive and support a nail-shaped anode collector, which, in turn, supports an outer negative terminal plate of the cell; the nail having a tapered body or shank to minimize assembly problems and to obtain optimum press-fit between the nail and the wall surface of the bore in said disc.

Another object of this invention is to provide said unitary plastic disc with a raised hub concentric with said central bore to have a long surface contact with said nail to inhibit or minimize electrolyte creepage along the nail shank.

The plastic disc, in order to fully utilize the desirable features of this invention, should have a slight resiliency, free of cold flow, with a memory that will tend to restore the plastic disc to its initial or original position after it has been slightly deformed by pressure. In the present case, where the outer rim edge of the can is crimped over the outer and upper surface of the plastic top, such crimping is intentionally slightly overpressed, but within the elastic limit of the metal, so that the crimped metal will have a slight tendency to move backward towards its original position, upon release of the crimping force, and thereby slightly relieve the pressure on the compressed and deformed plastic disc surface. Due to its resilience, the plastic disc material will also tend to move toward its original position and will follow the crimped metal of the can through the slight return movement of that crimped metal, to thereby maintain the tight reaction pressure between the crimped metal of the cathode can and the engaged surface of the plastic disc.

Since the plastic disc is supported on the bead of the can by the shoulder or inward step around the periphery of the plastic top, and, at the same time, is also held by the crimped material of the cathodic metal cup or can, the bead and the crimped material act essentially as the two jaws of a pincer to hold the plastic top in a tight grip. This assures better seal characteristics at the crimp.

One of the objects of this invention is to provide a unitary plastic cell top or disc with a resilient vertical edge portion in a position to receive the crimp from the container can for better seal characteristics at such crimp.

This pincer feature in itself is sufficient to assure good sealing between those two surfaces that are held under pressure against each other, but the invention includes an additional feature which impresses an additional pressure force on the crimped material to essentially lock the clamping and pincer action on the plastic disc, for complete and final assurance that the pincer grip on that plastic disc will be retained for the life of the cell, and leakage of electrolyte completely prevented from working along those engaging surfaces.

Thus, another object of this invention is to provide a novel and improved crimp at the end of a cell can, which places an additional external pressure on the sealing crimp on the plastic disc, to maintain said pincer effect by holding the original crimp against its natural resiliency and consequent tendency to spring back."

101036 n on To achieve such additional compression or pressure force on the crimped end section of the can, a metal jacket is disposed around the'steel cathode can and is suitably insulated therefrom as, for example, by an intermediate paper tube. The metal jacket, open at both ends originally, is then suitably itself crimped at both ends together with the paper insulating tube, and is essentially placed in tension, to press a negative metal cap as an electrode terminal at one end of the cell, and to press a positive metal cap at the other end of the cathode can of the cell, to permit simple connection of the final electrochemical cell as an element in an external circuit.

As previously indicated, the needs of the electrochemical batteries are such, that a primary object of the invention is to provide a simple and economic construction in which at her metic seal is assured, so that no leakage of electrolyte will occur from the internal structure of the cell and move to the outside of the cell closure, and, also, so that no creepage of electrolyte will occur between two regions that should be kept separated.

The nail, as anode collector, is electrically connected directly to the outer negative metal cap or plate. The metal cap is welded to the head of the nail. The nail is preferably made of alloy, commercially termed nickel silver, to be compatible with the anode material and to provide good resistance welding characteristics for welding to the plate. Alloys of 8 to 18 percent nickel have been found satisfactory.

Another object of this invention is to provide said unitary plastic disc having a relatively long bore surface engaged by said nail shank to prevent electrolyte creepage along the bore or nail surface to protect a weld between the flat head top surface of said nail and an outer negative terminal plate or cap.

Another object of this invention is to provide said unitary plastic disc with a depending circular apron for acting upon and substantially closing a separator structure to confine the electrolyte therein to minimize creepage of the electrolyte from its intended place within the container.

Another object of this invention is to dispose said plastic disc and said separator in adjacent relation with no intervening member between the plastic disc structure and said separator.

Another object of the invention is to provide a sealing structure for the cell in which a simple and economical mechanical assembly of the anode nail of the cell is provided, which will permit simple and ready manipulation, either manually or by automatic means, for assembling the anode structure into and in the cell in a proper desired position for final assembly and closure of the cell as a finished manufactured article.

' The details of construction of a cell made in accordance with the present invention, and various features of the cell, are more fully explained in the following description, taken together with the accompanying drawings, in which FIG. 1 is a schematic external perspective view of a typical cell body, embodying this invention;

FIG. 2 is a vertical mid-section through the cell of FIG. 1 taken along the line 2-2 in FIG. 1, and shows the various elements of the cell and their general arrangement within the shell enclosure, and relative to each other;

FIG. 3 is an exploded view of the elements that enter into the structure and assembly of the anode collector and supporting plastic disc when assembled and disposed as shown in position in FIG. 2;

and FIG. 4 is plan view of the disc to show radial re-inforcing ribs formed on the upper part thereof.

As shown in FIG. 1, a cell constructed in accordance with the present invention is shown in perspective merely to illustrate its external appearance.

As shown in FIG. 2, a cathode can 12, which may be of steel, and is closed at the bottom and originally open entirely at the top, serves as the main container for the elements of the cell. An annular cylinder 14 of cathodic material, to serve as a depolarizer, and consisting essentially of MnO mixed with graphite or carbon particles, is of proper size and shape to fit snugly within can 12 upon direct axial insertion into the steel cathode can 12. A separator 16 is disposed as a lining in the cathode material 14, and is shown here, for simplicity, and merely by way of example, as consisting of a concentrically fitted element of a suitable electrically insulating pouous material, defining a main central chamber 18 to receive an electrolyte anode member 20, into which may be easily inserted an anode collector element in the form of a nail 22.

The anode electrolyte material of the battery, including zinc pellets and a mixture of KOH and ZnO is then put into the central chamber 18 within the separator 16, and the cell is now ready to receive its anode collector 22, in the form of a nail, which is supported on a closure assembly consisting generally of the elements shown in FIG. 3.

To simplify the explanation relating to the construction and assembly of the closure element, which also serves to support the anode collector in the shape of nail 22, all of those elements will be described with reference first to FIG. 3, and then their assembled disposition will be considered'in the final construction as shown in FIG. 2.

As shown in FIG. 3 (a), the anode collector 22 at the top of the figure consists of a nail-shaped element having a fiat head 24, a downwardly converging tapered partial shank 26 and an elongated main shank 28. Shown resting on the nail head 24 is a circular plate 30 that is spot-welded to the nail head 24 prior to assembly of the cell, to serve as an outer plate terminal for the cell. Said plate terminal 30 has a central circular area portion 32, a downward encircling rim 34, an annular moat ring 36 and an encircling crimped eye 38.

In FIG. 3 (b) is shown an annular ring 40, of insulating material, such as relatively hard but slightly compressible paper, with a central bore 42.

In FIG. 3 (c), is shown a unitary circular cell cap 46, of plastic material having a slight compressibility and memory, to tend to return to an original shape and physical disposition after an external compression force is removed.

The plastic cell cap 46 in FIG. 3 (c) is circular in shape to fit into the can 12, and has a central axial bore 48 of appropriate dimension to receive the slightly tapered body shank 26 of the nail 22, with a tight press fit. The centrial axial bore 48 is surrounded by a boss or hub 50 with an internal bearing surface 52 that is relatively long, in order to provide a long sealing path between that central bore surface 52 and the body shank 26 of the anode nail 22 in the assembly. Also, the relative dimensions of the bore diameter and the shank diameter provide for a tight press fit. The top surface 54 of hub 50 serves as a seal for the nail head 24.

The plastic cap 46 also has a circular peripheral border rim 56 which rises above the annular body floor plate 58, which makes the plastic disc a relatively rigid structure. In addition, in order to provide for additional reinforcement between the central hub 50 and the peripheral border rim 56, there are several radial ribs 60 distributed in a wheel-spoke fashion between the hub 50 and the peripheral border rim 56.

The border rim 56 of the plastic cap 46 is peripherally provided with a radially inward shoulder 62, that is to serve, in part, as the seating surface of the plastic cap 46 when assembled in the final assembly of the cell.

The plastic cap 46 is further provided with a depending circular and concentric annular apron 64, near the rim of the cap, whose purpose and function will be described in connection with the assembly of FIG. 2.

Referring back to the nail 22 of FIG. 3 (a), it will be seen that the body shank 26 is tapered increasingly upwardly to assure a tight pressure fit in bore 48 of plastic cap 46. The flathead 24 on anode collector in the shape of nail 22 serves as a supporting surface to receive the negative cap terminal 30 which is spot-welded thereto before assembly.

To paper insulating ring 40 in FIG. 3 (b) has a bore 42 of such dimension as to fit over the hub 50 of plastic cap 46, shown in FIG. 3 (c). In the final assembly, said washer 40 will be seated on the crimp of the end of tube 12 to provide an insulating seat for said outer negative end cap terminal 30, as in FIG. 2.

In FIG. 3 (d) the cell is shown at an intermediate stage of manufacture. The can 12 has received the depolarizer chemical elements 14 and the separator 16, and the internal bead 66 has been formed, prior to filling with the electrolyte to the level shown, before the nail anode collector 22 is inserted. The separator 16 is erect, as in solid line, before being folded toward closure, as in dash line, by the apron 64 on the plastic cap 46, when said cap 46 is seated on the bead 66 in the can 12 to close the cell.

Referring now back to FIG. 2, it may be explained that after the insertion of the cathodic material 14 within the original cathode tube 12, the bead 66 is formed peripherally around the inner surface of the tube to extend radially inwardly, to serve as a circular seat for said plastic cap 46 at the undercut shoulder 62 formed in the periphery of that plastic cap 46, as shown in FIG. 3 (c).

After the inner bead 66 is formed in the cathode tube 12, the open end rim of the tube is still in its original open condition as shown in FIG. 3 (d), thereby permitting the assembly of the separator 16, the electrolyte 20, and the anode collector in the shape of nail 22 from FIG. 3 (a), to be inserted into that open inner steel can 12 and pressed axially inwardly down until the plastic cap 46 is seated upon said bead 66.

In order to obtain the desired good sealing conditions within the cell, the dimensions of the plastic cap 46 should be such as to require a relatively pressed-fit into the cathode steel tube 12, so that the seating corner edge at the edge of the shoulder 62 will fit snugly within the tube 12 and will position the entire assembled unit relatively co-axially and concentrically within the final cell. The surface 68 depending directly down from the stepped shoulder 62 on the plastic cap 46 may also be dimensioned to fit relatively snugly against and diametrically within the bead 66.

As previously explained, after the cathodic depolarizer material 14 is inserted and the separator 16 is placed in position, and the electrolyte disposed within the separator space, the cell is ready to receive the anode collector nail 22.

Another advantageous feature of this invention will now be appreciated. Since, in many cases, the cells are relatively small, the component parts are correspondingly small and require careful and fine handling. That is particularly so in the operation of positioning the anode collector. Here, the anode collector is more readily manipulatable since it is welded to and supported on the plate terminal 30, which now also serves as a handle for manipulating the anode collector in the shape of nail 22, so this desirable function as a handle is available for manual or automatic operations.

When the plastic cap is in place, the anode nail collector assembly is inserted co-axially into the can 12, through plastic cap 46, and the anode collector 22 can be forced down into the electrolyte with relatively light pressure, even though the electrolyte will have in the meantime absorbed the zinc powder pellets within the separator 16 that serves as an ionic exchange member and barrier between the anode compartment and the cathodic depolarizer material.

After the plastic disc 46 is seated on bead 66, the first crimping operation is performed to crimp the open edge end 70 of the open can 12 onto the top surface of the border rim 56 of the plastic cap 46.

This part of the operation of sealing the cell also embodies an important feature of the invention in this construction. The material which has been found particularly suitable for the use desired here in the plastic cap 46 is nylon. It has the characteristics previously described as desirable, in that it will accept a certain amount of compression and has a memory characteristic which tends to restore it to its original condition. Said crimping metal 70 at the outer end of the metal cathode can 12 is therefore overpressed during assembly so that it will press the nylon material of the cap 46 more than is necessary for a good seal, but since such pressure of the metal is within the elastic limit of the metal, the crimped metal portion 70 tends to return slightly towards its original condition and thus tends to relieve some of the pressure initially impressed on the nylon material. However, the nylon material, when so relieved, follows the relieving return movement of the crimped metal portion 70 and maintains a continuing high pressure surface-to-surface relationship and seal between the nylon material and the crimped metal 70 of the can 12, to prevent creepage of any electrolyte material that might be moved into that area as the cell is externally and manually manipulated for any reason.

In order to maintain that high pressure surface-to-surface relationship between the plastic cap material and the crimping metal of the can, an additional extremely important feature is provided here. Said annular washer 40 of insulating material, such as hard paper, for example, previously referred to in FIG. 3 (12), now comes into service, and is seated on top of the crimped metal 70 that overlays the top of the border rim 56 of the plastic cap 46. That paper ring washer 40 also has certain desirable characteristics. It is preferably made of paper that is relatively hard and only slightly compressible to provide both electrical insulating qualities and some pressure-resistance to be able to transmit pressure force onto the crimped metal overlay. In assembly, that paper ring 40 overlying the crimped metal 70 is placed and kept under permanent pressure that will be now explained.

The application of the paper ring 40 onto the crimped metal 70 of can 12, and the additional pressure on that paper ring 40 that will be applied, as will be explained below, tends to place an external pressure on the crimped metal 70 in such a way as to make it practically impossible for that crimped metal to shift away from the engaged upper surface of the border rim 56 of the plastic disc 46. With that additional pressure on the crimped metal, a completely effective seal is assured, so that any of the electrolyte that might otherwise get into the area of the bead, that normally should never occur, but might because of actual or undesired external manual manipulations of the cell, would nevertheless by unable to move upward and outward out of the inner space of the cell structure, to engage any outer metal.

The manner in which the extra pressure is applied to the paper annulus 40 may now be considered.

As shown in FIG. 2, the container can 12 is surrounded by a layer of insulating material such as a paper tube 80, and then an external steel jacket 82 is applied to surround the paper tube 80.

After the operation of positioning the plastic cap 46 in said can 12, the open rim of can 12 is crimped onto the border rim 56 of said plastic cap 46. The paper ring 40 is then placed in position on said crimp 70 of can 12, and the pre-formed negative end cap 30 is seated on said paper ring 40 as the nail 22 is pressed downwardly through the plastic cap 46. The cap terminal 30 is then crimped at said position to apply pressure onto said paper ring 40, and, through said paper ring, onto the first metal crimp 70 of can 12.

The outer negative end cap terminal 30 is provided with a large circular plate 32 with a lower depending rim or apron 34 and a horizontal annular seating and pressure ring 36, and an encircling crimped eye 38, shown in detail in H6. 3 (a).

Returning to the assembly in FIG. 2, said seating and pressure annular ring 36 of said outer negative end cap terminal 30 seats on the paper ring annulus 40. The pressure impressed on that seating and pressure annulus 36 of negative cap terminal 30 is applied through said crimped dye 38 by an encircling and crimping bend 84 at the upper end of said outer steel jacket 82. Said upper steel crimping bend 84 is insulated from said negative cap terminal 30 by said paper tube disposed between said inner steel tube 12 and said steel jacket 82 and extending upward beyond the first metal crimp 70.

At the other end, said steel jacket 82 is similarly provided with a semi-circular bend 86 to press the circular crimped eye 88 of a contact terminal cup 90 into engagement with the bottom surface of said inner can 12, so that the contact terminal 90 may serve as a contact button for connection to an external elecmcal circuit. Said crimped eye 88 of that contact terminal 90 is similarly insulated from the external metal jacket 82 by said paper tube 80 extended.

It will now be seen that the steel jacket 82 serves as a pressure producing device anchored at the bottom of the cell and extending to the top of the cell to create the pressure on the paper annular pressure ring 40 that will press down on the crimped metal 70 of the inner can 12 and assure practically permanent and tight surface-to-surface relationship between the crimped metal portion 70 of the inner can 12 and the upper surface of said annular border rim 56 of said plastic cap 46, thereby preventing electrolyte creepage, and thereby ensuring that the cell will remain both operative and clean on its outer surface throughout shelf life.

The surfaces on the shank of said nail 22 and on said bore 48 of the plastic disc are also maintained under heavy pressure by reason of the press-fit between them, and the pressure reaction of said annular border rim 56 of said plastic cap 46, working back through said radial webs 60 on said plastic cap 46, as in FIG. 4.

A further feature remains to be discussed. In FIG. 3, the depending apron 64 of said plastic disc is shown. In FIG. 2 said apron 64 is seen to be accommodated by a small annular space 120 above the cathode material, and the apron 64 extends downward to surround the top open end of the separator 16. The separator is now seen turned inward and crimped to closer position with respect to the top of said anode collector in the shape of nail 22, so that very little space is left for the electrolyte to move into, out of the separator. The plastic cap 46 serves this additional function of essentially closing the separator to reduce the space through which any electrolyte might escape from its working region. Thus the electrolyte can engage only said plastic cap 46 beyond its working region, and is effectively confined, so it cannot reach other regions and cause erosive effects.

The alloy referred to herein for nail 22, is an alloy of copper, zinc and nickel, that is commercially known as nickel silver, although it has no silver ingredient. The alloy has been found suitable with a nickel content over the range from 8 to 18 percent.

The invention has been described in connection with one form of the invention to show a preferred operative form which has served the purpose of the invention and functions as intended. It is obvious that modifications might be made in the dimensions and in the relative design of the individual structural parts without departing from the spirit and scope of the invention, however, as described in the claims.

What is claimed is:

l. A primary battery cell, comprising a cylindrical metal can, closed at its bottom and open at its top; an annular filling of cathodic or depolarizer material adjacent the inner surface of the wall of said can; an annular lining within said cathodic depolarizer material and constituting an ionic exchange membrane separator defining a central axial chamber; said separator being of diameter smaller than the can and the depolarizer material; an anode electrolyte within said axial chamber; an anode collector assembly, having an anode collector in the shape of a nail supported by said plastic cap gripping an area of the shank of said nail with a pressed-fit to establish a hermetic seal against seepage of the electrolyte therethrough; said plastic cap having an undercut shoulder formed at the periphery of the plastic cap and also having an apron downwardly extending into contact with said depolarizer material and being positioned between said shoulder and said collector nail to surround the top open end of the separator; a bead formed peripherally around the inner surface of said can to extend radially inwardly to serve as a direct contact circular seat for said plastic cap at said undercut shoulder; said separator having a top open end folded inwardly toward closure by the apron on the plastic cap when said cap is directly seated on the bead in the can to close the cell; and means for hermetically sealing the plastic cap over a border surface area of said plastic cap by a crimped-over end of the can to prevent electrolyte seepage over that area; and an external closing terminal plate for the cell which seals the anode collector assembly wholly within the cell can and prevents said plastic cap from extending outside of said cell can.

2. A primary battery cell as in claim 1, in which said plastic cap element has an axially extending raised central hub portion, having a central co-axial bore and having an annular upper end face;

and said nail anode collector has a flat head whose under surface rests on said annular upper-end face of said hub portion, and said anode collector nail has a shank dimension to fit tightly into said central co-axial bore when inserted and pressed thereinto, and said anode collector nail further has a continuing shank extension to extend axially into the electrolyte in the central axial chamber of said cell;

and an external closing terminal plate for the cell which engages and rests on said flat head of said anode collector nail, and is electrically welded to said flat head.

3. A primary cell, as in claim 2, in which said external closing terminal plate is spot welded to said flat surface on said nail head, to provide the electrical connection from said nail-shaped anode collector to said external terminal plate;

and said anode collector nail is made of an alloy having a nickel content to provide good resistance welding characteristics, as exhibited with nickel contents of 8 to 18 percent.

4. A primary battery cell, as in claim 2, in which said closing terminal plate embodies a central flat surface circular area, with a circular rim surrounding said central area, and disposed to press on said crimped-over end of said metal can through an insulating medium.

5. A primary battery cell, as in claim 4, including, further,

an insulating member disposed and held between said circular rim of said terminal plate and the top surface of said crimped-over end of said cathode can, to insulate said terminal plate connected to the anode nail from the crimped end of the cathodic can.

6. A primary battery cell, as in claim 5, in which said terminal plate embodies an encircling rim;

an insulating tube encircles said can;

a metallic jacket tube encircles said insulating tube with one crimped-over end of said metallic jacket tube crimping the corresponding end of said insulating tube on said encircling rim of said terminal plate, and the crimped-over other end of said metallic jacket tube is anchored at the corresponding other end of said cylindrical metal can.

7. A primary battery cell, as in claim 6, in which a terminal means is disposed at the bottom end of said cylindrical metal can;

and said crimped-over other end of said metallic jacket tube is insulatingly secured to said terminal means at said bottom end to hold said terminal means electrically in contact with said bottom of said cylindrical metal can.

i l l i nun-1a 

1. A primary battery cell, comprising a cylindrical metal can, closed at its bottom and open at its top; an annular filling of cathodic or depolarizer material adjacent the inner surface of the wall of said can; an annular lining within said cathodic depolarizer material and constituting an ionic exchange membrane separator defining a central axial chamber; said separator being of diameter smaller than the can and the depolarizer material; an anode electrolyte within said axial chamber; an anode collector assembly, having an anode collector in the shape of a nail supported by said plastic cap gripping an area of the shank of said nail with a pressed-fit to establish a hermetic seal against seepage of the electrolyte therethrough; said plastic cap having an undercut shoulder formed at the periphery of the plastic cap and also having an apron downwardly extending into contact with said depolarizer material and being positioned between said shoulder and said collector nail to surround the top open end of the separator; a bead formed peripherally around the inner surface of said can to extend radially inwardly to serve as a direct contact circular seat for said plastic cap at said undercut shoulder; said separator having a top open end folded inwardly toward closure by the apron on the plastic cap when said cap is directly seated on the bead in the can to close the cell; and means for hermetically sealing the plastic cap over a border surface area of said plastic cap by a crimped-over end of the can to prevent electrolyte seepage over that area; and an external closing terminal plate for the cell which seals the anode collector assembly wholly within the cell can and prevents said plastic cap from extending outside of said cell can.
 2. A primaRy battery cell, as in claim 1, in which said plastic cap element has an axially extending raised central hub portion, having a central co-axial bore and having an annular upper end face; and said nail anode collector has a flat head whose under surface rests on said annular upper-end face of said hub portion, and said anode collector nail has a shank dimension to fit tightly into said central co-axial bore when inserted and pressed thereinto, and said anode collector nail further has a continuing shank extension to extend axially into the electrolyte in the central axial chamber of said cell; and an external closing terminal plate for the cell which engages and rests on said flat head of said anode collector nail, and is electrically welded to said flat head.
 3. A primary cell, as in claim 2, in which said external closing terminal plate is spot welded to said flat surface on said nail head, to provide the electrical connection from said nail-shaped anode collector to said external terminal plate; and said anode collector nail is made of an alloy having a nickel content to provide good resistance welding characteristics, as exhibited with nickel contents of 8 to 18 percent.
 4. A primary battery cell, as in claim 2, in which said closing terminal plate embodies a central flat surface circular area, with a circular rim surrounding said central area, and disposed to press on said crimped-over end of said metal can through an insulating medium.
 5. A primary battery cell, as in claim 4, including, further, an insulating member disposed and held between said circular rim of said terminal plate and the top surface of said crimped-over end of said cathode can, to insulate said terminal plate connected to the anode nail from the crimped end of the cathodic can.
 6. A primary battery cell, as in claim 5, in which said terminal plate embodies an encircling rim; an insulating tube encircles said can; a metallic jacket tube encircles said insulating tube with one crimped-over end of said metallic jacket tube crimping the corresponding end of said insulating tube on said encircling rim of said terminal plate, and the crimped-over other end of said metallic jacket tube is anchored at the corresponding other end of said cylindrical metal can.
 7. A primary battery cell, as in claim 6, in which a terminal means is disposed at the bottom end of said cylindrical metal can; and said crimped-over other end of said metallic jacket tube is insulatingly secured to said terminal means at said bottom end to hold said terminal means electrically in contact with said bottom of said cylindrical metal can. 